Holley Problems?!

79Stang · 01-20-2001, 05:10 PM

I was having some idle problems with my Holley 750 (vac. sec) so pretty much rebuilt the carb. I'm still having the same problem's though... I have a ruff idle and and I can tighten one of the mixture screws all the way down and the car will still run... The float level is fine, installed new needle/seats...

I am gonna hook up a Vacuum gage and see where that takes me, but any ideas?????

Thanks!

pro88 · 01-20-2001, 10:10 PM

How big are the jets that you have in it now? It really sounds like you're jetted way too fat. Go down on your jet sizes 4 at a time. I have a Holley 3310(750 vac. sec.)on my '79 stang driver now. That was my problem. Mine acted the same way you're describing. I've got size 66's in the primary and it is a little bit on the rich side but I'd rather have it a little rich than too lean. When I adjust my air/fuel screws, I'm at 1 1/2 turns where it runs the best.

Idhomustang · 01-20-2001, 10:44 PM

I agree completely your way to rich if you can screw in your idle mixture screws and it keeps running. Did you adjust the needle and seats were the fuel just barely trickles down the outside of the fuel bowl that would be right.
Another thing to check is the power valve, did you replace it during the rebuild sometimes they go bad and cause the flooding like symptoms you are discribing as well. Good Luck.

IHM.

------------------
393,9.5" 351W
830 Holley HP
Victor Jr.
Home made Cool Air Pan
Pro Billet MSD

79Stang · 01-21-2001, 10:49 AM

Not sure on the Jet size - I could check on the Holley page, it's what ever came with the 'Trick Kit.' I'll order some jets, 6 below what ever I find I have?

I always thought that if you had bad idle problems must be the power valve, but the power valve has nothing to do with idle quality. (According to Holley) but, yea I put a new 6.5 in there with the rebuild..

Also, I notice that idle quality when I first start it up seems better then 30sec after the start up - Yea, it's running ritch, but the floats are good, messed with them for awhile yesterday... I'll go check those jet sizes and get back with you guys!

79Stang · 01-21-2001, 11:02 AM

Just checked - primary jets are 72's - so 66's for me????

What size motor pro88???

pro88 · 01-21-2001, 04:46 PM

I'm running a 302 with a mild cam. I'd go ahead and put the 66's in the primary, it'll be a good starting point for you. What motor are you running-I mean what's in it. All mine is, is a .440/.260 cam in mine, Edlebrock F4B intake and a freshening of the bearings. Put the 66's in, see how far you have to screw your air/fuel out. It it's past 2 turns go 2 sizes up. If it's less than 1 1/2 turns, go with 2 sizes down and kinda play with it until you get what you want. Double check you needle/seat for any dirt. Because even a speck will mess things up for you. Let us know!!

By the way, you have a good choice in power valve.

79Stang · 01-21-2001, 05:35 PM

I have a 351 thats .030 over, Comp Cam with about .501 lift, Edlbrock RPM, 'mild head work'... I just sent in a order for 66's... I'll tell u how it goes...

Rev · 01-21-2001, 07:21 PM

I hate to disagree here, but the main jets are part of the main metering circuit and not part of the idle circuit in Holley carbs. Rich idle can be caused by a leaking needle & seat on the pimary or secondary side. If you look into the secondaries, a drip into the secondary bores can be seen if the inlet valve is allowing the secondary bowl to overfill. The same applies to the primary side. A leaking power valve on the primary side will allow extra fuel to drip in from the main metering orifice on the primary side. Changing the main jets won't help either of these problems or affect the idle in any way. Look for other ways that extra fuel is coming in. My $.02.

Rev

------------------
'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

pro88 · 01-21-2001, 08:23 PM

My drag car has a 351W. I've done the heads(I've got the 1.84/1.55 valves-'69 heads, motor is '70 351W. I'm running a hyd.544/.244 Comp Cams bump stick. Compression is 10.7 to 1, single plane intake. I'm running a Holley 4777(650 dbl.) I've got 74's in the front and 79's in the rear. Out of comparison with my driver and this motor my guess you'll end up with 68 jets. What you need to do is go ahead and save yourself money in the long run by buying a Holley jet kit. Those only run about $40.00. By the time you buy jets singly, you'll end up spending more than that. Let us know.

79Stang · 01-26-2001, 12:06 PM

Just got done installing the 66's and the power gains are crazy! I was really over jetted!! I thought they where 72's, nope 74's!

BUT, I must have a internal leak somewhere! I can still tighten down one side and the car will idle! I'm going to look at the drawing on the Holley site -

Any other IDEAS?

thanks!

------------------
°79Stang° • 351w, TRW Flat Tops, Comp Cam 270h,Edelbrock RPM Intake,
Holley 750 Duel Feed, MSD-6a, 2,500 stall,
Flowmasters, MaC shorties, B&M Shift Kit, Hurst Pro-Matic][,
DrAgLiTES on all four's
No Times yet - heads on the way

pro88 · 01-26-2001, 09:54 PM

I would check for vacuum leaks somewhere. Start at your carb base and all around it. Drop your jets to 64's and start turning your screws, you might still have too much fuel. Also check the power valve gasket inside and make sure it's centered.

79Stang · 01-27-2001, 09:10 AM

I'm gonna go through it again, I can't go down in jet size anymore - I think the 66's are starving it...

Five0 · 01-27-2001, 09:50 AM

Hey 79stang, one of my friends where we hang out on Saturday night is a mechanic for ford and has a car like yours with a 351w and he can help you get it tuned right. I don't have to work tonight after all, so if you want to meet somewhere we can meet around 9:30 pm at the Kmart on Blanding just past 103rd on the right. We will be out there so if you’re coming I will see you there. If you want to call me to be more specific I will e-mail you my #.

BTW: I drive a black '91 notchback w/weld wheels and dark tinted windows.

------------------
James Cox
nochevy@hotmail.com
1991 Mustang LX
12.565 @109.38mph 1.764 60ft

79Stang · 01-28-2001, 01:06 PM

Didn't get the email in time - I'll come out there though.. Try next weekend...

Later!

Five0 · 01-28-2001, 03:23 PM

ok, let me know.

------------------
James Cox
nochevy@hotmail.com
1991 Mustang LX
12.565 @109.38mph 1.764 60ft

Dangerous Dave · 01-29-2001, 12:41 PM

Rev is right...changing the jets will not have any effect on your idle problem. If you saw a trail of black smoke at WOT down the road then you would most likely be over jetted but there is something else wrong-doesn't sound like an adjustment problem. Check powervalve condition, also check to see if fuel is dripping out of the squirter. Make sure the check ball inside the accelerator pump housing hasn't fallen out-I've seen this happen before too.
BTW-750 Holleys come stock with 72 jets. You may be able to tune it to go faster with different jets but will not fix this problem.
You've got to find the right combo when you tune it though. 600 Holleys come stock with 65 jets. You can jet down all you want with the 750 but you are still letting in 750 cfm of air. If you're gonna run 66 jets-find some one that will let you borrow a 600 or just go buy one-can usually find them for $50-$75. If I were a betting man...I'd put all my dough on the 600 being faster-I've experimented with this before. On a near same setup you have.

------------------
1988 GT-under construction

79Stang · 01-29-2001, 01:49 PM

Thats correct stock is 72, but I had 74's in mine - not a brand new carb. The power valve is brand new and that like the jetting - no effect on idle. I'm going to check the checkball though. Could have fell out during rebuild.

I had a 600 on there before the 750 - I had much better idle, but not as much performance at WOT -

79Stang · 01-29-2001, 02:00 PM

Should there be 2 secondary metering plate gaskets??? The kit comes with two, and they are both the same size.... Thanks!

01-20-2001, 05:10 PM	#1
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Holley Problems?! I was having some idle problems with my Holley 750 (vac. sec) so pretty much rebuilt the carb. I'm still having the same problem's though... I have a ruff idle and and I can tighten one of the mixture screws all the way down and the car will still run... The float level is fine, installed new needle/seats... I am gonna hook up a Vacuum gage and see where that takes me, but any ideas????? Thanks!

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01-20-2001, 10:10 PM	#2
pro88 Registered Member Join Date: Dec 2000 Location: roseburg, oregon Posts: 87	How big are the jets that you have in it now? It really sounds like you're jetted way too fat. Go down on your jet sizes 4 at a time. I have a Holley 3310(750 vac. sec.)on my '79 stang driver now. That was my problem. Mine acted the same way you're describing. I've got size 66's in the primary and it is a little bit on the rich side but I'd rather have it a little rich than too lean. When I adjust my air/fuel screws, I'm at 1 1/2 turns where it runs the best.

01-20-2001, 10:44 PM	#3
Idhomustang Registered Member Join Date: Sep 1999 Location: boise,idaho Posts: 220	I agree completely your way to rich if you can screw in your idle mixture screws and it keeps running. Did you adjust the needle and seats were the fuel just barely trickles down the outside of the fuel bowl that would be right. Another thing to check is the power valve, did you replace it during the rebuild sometimes they go bad and cause the flooding like symptoms you are discribing as well. Good Luck. IHM. ------------------ 393,9.5" 351W 830 Holley HP Victor Jr. Home made Cool Air Pan Pro Billet MSD

01-21-2001, 10:49 AM	#4
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Not sure on the Jet size - I could check on the Holley page, it's what ever came with the 'Trick Kit.' I'll order some jets, 6 below what ever I find I have? I always thought that if you had bad idle problems must be the power valve, but the power valve has nothing to do with idle quality. (According to Holley) but, yea I put a new 6.5 in there with the rebuild.. Also, I notice that idle quality when I first start it up seems better then 30sec after the start up - Yea, it's running ritch, but the floats are good, messed with them for awhile yesterday... I'll go check those jet sizes and get back with you guys!

01-21-2001, 11:02 AM	#5
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Just checked - primary jets are 72's - so 66's for me???? What size motor pro88???

01-21-2001, 04:46 PM	#6
pro88 Registered Member Join Date: Dec 2000 Location: roseburg, oregon Posts: 87	I'm running a 302 with a mild cam. I'd go ahead and put the 66's in the primary, it'll be a good starting point for you. What motor are you running-I mean what's in it. All mine is, is a .440/.260 cam in mine, Edlebrock F4B intake and a freshening of the bearings. Put the 66's in, see how far you have to screw your air/fuel out. It it's past 2 turns go 2 sizes up. If it's less than 1 1/2 turns, go with 2 sizes down and kinda play with it until you get what you want. Double check you needle/seat for any dirt. Because even a speck will mess things up for you. Let us know!! By the way, you have a good choice in power valve.

01-21-2001, 05:35 PM	#7
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	I have a 351 thats .030 over, Comp Cam with about .501 lift, Edlbrock RPM, 'mild head work'... I just sent in a order for 66's... I'll tell u how it goes...

01-21-2001, 07:21 PM	#8
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	I hate to disagree here, but the main jets are part of the main metering circuit and not part of the idle circuit in Holley carbs. Rich idle can be caused by a leaking needle & seat on the pimary or secondary side. If you look into the secondaries, a drip into the secondary bores can be seen if the inlet valve is allowing the secondary bowl to overfill. The same applies to the primary side. A leaking power valve on the primary side will allow extra fuel to drip in from the main metering orifice on the primary side. Changing the main jets won't help either of these problems or affect the idle in any way. Look for other ways that extra fuel is coming in. My $.02. Rev ------------------ '66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph 1/4 mi.

01-21-2001, 08:23 PM	#9
pro88 Registered Member Join Date: Dec 2000 Location: roseburg, oregon Posts: 87	My drag car has a 351W. I've done the heads(I've got the 1.84/1.55 valves-'69 heads, motor is '70 351W. I'm running a hyd.544/.244 Comp Cams bump stick. Compression is 10.7 to 1, single plane intake. I'm running a Holley 4777(650 dbl.) I've got 74's in the front and 79's in the rear. Out of comparison with my driver and this motor my guess you'll end up with 68 jets. What you need to do is go ahead and save yourself money in the long run by buying a Holley jet kit. Those only run about $40.00. By the time you buy jets singly, you'll end up spending more than that. Let us know.

01-26-2001, 12:06 PM	#10
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Just got done installing the 66's and the power gains are crazy! I was really over jetted!! I thought they where 72's, nope 74's! BUT, I must have a internal leak somewhere! I can still tighten down one side and the car will idle! I'm going to look at the drawing on the Holley site - Any other IDEAS? thanks! ------------------ °79Stang° • 351w, TRW Flat Tops, Comp Cam 270h,Edelbrock RPM Intake, Holley 750 Duel Feed, MSD-6a, 2,500 stall, Flowmasters, MaC shorties, B&M Shift Kit, Hurst Pro-Matic][, DrAgLiTES on all four's No Times yet - heads on the way

01-26-2001, 09:54 PM	#11
pro88 Registered Member Join Date: Dec 2000 Location: roseburg, oregon Posts: 87	I would check for vacuum leaks somewhere. Start at your carb base and all around it. Drop your jets to 64's and start turning your screws, you might still have too much fuel. Also check the power valve gasket inside and make sure it's centered.

01-27-2001, 09:10 AM	#12
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	I'm gonna go through it again, I can't go down in jet size anymore - I think the 66's are starving it...

01-27-2001, 09:50 AM	#13
Five0 Registered Member Join Date: Apr 2000 Location: middleburg, fl, usa Posts: 1,134	Hey 79stang, one of my friends where we hang out on Saturday night is a mechanic for ford and has a car like yours with a 351w and he can help you get it tuned right. I don't have to work tonight after all, so if you want to meet somewhere we can meet around 9:30 pm at the Kmart on Blanding just past 103rd on the right. We will be out there so if you’re coming I will see you there. If you want to call me to be more specific I will e-mail you my #. BTW: I drive a black '91 notchback w/weld wheels and dark tinted windows. ------------------ James Cox nochevy@hotmail.com 1991 Mustang LX 12.565 @109.38mph 1.764 60ft

01-28-2001, 01:06 PM	#14
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Didn't get the email in time - I'll come out there though.. Try next weekend... Later!

01-28-2001, 03:23 PM	#15
Five0 Registered Member Join Date: Apr 2000 Location: middleburg, fl, usa Posts: 1,134	ok, let me know. ------------------ James Cox nochevy@hotmail.com 1991 Mustang LX 12.565 @109.38mph 1.764 60ft

01-29-2001, 12:41 PM	#16
Dangerous Dave Registered Member Join Date: Sep 1999 Location: Minneapolis, MN Posts: 121	Rev is right...changing the jets will not have any effect on your idle problem. If you saw a trail of black smoke at WOT down the road then you would most likely be over jetted but there is something else wrong-doesn't sound like an adjustment problem. Check powervalve condition, also check to see if fuel is dripping out of the squirter. Make sure the check ball inside the accelerator pump housing hasn't fallen out-I've seen this happen before too. BTW-750 Holleys come stock with 72 jets. You may be able to tune it to go faster with different jets but will not fix this problem. You've got to find the right combo when you tune it though. 600 Holleys come stock with 65 jets. You can jet down all you want with the 750 but you are still letting in 750 cfm of air. If you're gonna run 66 jets-find some one that will let you borrow a 600 or just go buy one-can usually find them for $50-$75. If I were a betting man...I'd put all my dough on the 600 being faster-I've experimented with this before. On a near same setup you have. ------------------ 1988 GT-under construction

01-29-2001, 01:49 PM	#17
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Thats correct stock is 72, but I had 74's in mine - not a brand new carb. The power valve is brand new and that like the jetting - no effect on idle. I'm going to check the checkball though. Could have fell out during rebuild. I had a 600 on there before the 750 - I had much better idle, but not as much performance at WOT -

01-29-2001, 02:00 PM	#18
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Should there be 2 secondary metering plate gaskets??? The kit comes with two, and they are both the same size.... Thanks!